Apparatus for testing concrete and the like.



R. FRBER.

APPARATUS FOR TESTING CONCRETE AND THE LIKE.

APPLICATION FILED JAN. 4, 1912.

1,061,996. Patented May zo, 1913.

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UNITED sTATEs PATENT oEEioE.

RICHARD FRBER, 0E FRANKFQRT-ON-THE-MAIN, GERMANY, ASSIGNOR T0 THE FIRM 0F BUCHI-IEIM & IIEISTER, OF FRANKFURT-ON-THE-MAIN, GERMANY.

APPARATUS FOR `TESTING CONCRETE AND THE LIKE.

Specification of Letters Patent.

...Patented May 2o, 1913.

Appiicanon inea January 4, 1912. serial No. 669,333.

To all wh-0m t may concern Be it known that I, RICHARD FREER,

doctor of engineering, a subject of the German Emperor, residing at Frankfort-on-the- Main, in Germany, have invented certain new and useful Improvements in Apparatus for aTest-ing Concrete and the Like, of which the following is a specification. y

The primary objectof the present invention is to provide concrete testing'apparatus which is more compagt and easily portable than the apparatus heretofore used, and is adapted, without interchange of parts, both for tension and for compression tests.

Another object is to provide means whereby a single specimen of concrete can be used both for the tension and for thecompression test, thus effect-ing a saving of material and of the time required for preparingspecimens.

`The invention is illustrated in the accompanying drawing, in which Figures 1 to 3 represent a mold for preparing the specimen, Fig. 1 being a plan- View, Fig. 2 a cross-section-and Fig. 3 a side elevation, half in section. Fig. 4 is a side elevation, partly in section,` of the testing apparatus, with specimen, set up for the tensile strength test. Fig.` 5 is a similarV View, showing the apparatus set up for the compression test. Fig. 6 is a plan-view of the test-ing apparatus. i

' *The specimen mold .comprises a narrow iro-n plate a stiff but having acertain amount of elasticity, and having inclined projections (2 the ends of the said plate being curved around to meet the two projections b nearestthem. For forming the specimen, this plate is laid on the ground, with two narrow plates e placed on edge alongside it, to form walls, and the mold is then filled with the material to be tested, which will hereinafter be referred to as they concrete. The walls e are held together at their ends byclamps f; these, together with the walls e, are removed when the concrete has set. The mass of concrete, with the ironl plate a, then forms a short specimen beamg, standardized, in regard to its cross-section, by the widths of the plates a and e. The strength of the plate a is ascertained by previous measurement, so that measurement of the strength of-the specimen beam g, when subjected to transverse strain, affords an index tothe strength of the concrete, thestrength of the iron being a known quantity, which is deducted from the total resistance value. This beam or test piece g is placed upright on the lower member cl ofk the testing frame, as shown in Fig. 4. This member d engages the lower end of the test piece in the manner of a hook, and has a strut abutting against the plate a somewhat less than half way up the length of the piecer g. Asimilar, but inverted member r; is engaged with the upper end of the test-piece; the members c and (Z with their struts thus form a lever system whereby the piece can be subjected to a bending strain byepressure vapplied-to the free end of the member 0. By such pressure a tensile strain is imposed on the concrete at the right hand side of Fig. 4. The pressure is applied by means of a scale beam t, which rocks at u on a knife edgewith 'which the member e is provided. One arm of the scale beam is connected to the member IZ by rods e .e1 connected to each other by a turn-buckle y. To the other arm of the scale beam is connected a vessel z' positioned below the tap Z of a vessel 71:, so that liquid 'can be run from the vessel 7a to the vessel On the liquid in the vessel la rests a floatem,

attached to a cord m1 which passes around a .rotatable disk n, and has a weight p attached disk a. The dependingportion of the cord e nl with the weight attached thereto/serves as a plumb line indicating when the apparatus is placed accurately in upright rposi-` tion, the adjustmentl for this purpose being made by means of set screws fv. When the apparatus has been setup in the manner shown in Fig. ,4 the tap Zfis opened so that liquid flows slowly from theV vessel 7el to the vessel i and thus increases the load on one arm of the scale beam, the turn buckle y being at the same time operated so as to keep the beam in equilibrium. The scale beam arms and levers d `and c can easily be proportioned so that the effect of the added no i load, in regard to strain on the specimen g, is multiplied in the proportion of, say 240 to l, the multiplication by the levers c d being, say, by 6, and that by the scale beam, 40. While the miniature specimen beam g bends, the scale beam can easily be kept in equilibrium, so that the brake device g does not interfere With rotation of the disk n, and the amount of strain imposed at any moment can be read off the disk n, the scale on the latter being graduated for this purpose in accordance with the predetermined constants of the apparatus.

Then the breaking point is reached, and the concrete is fractured, as indicated at r in -F ig. Li, the scale beam suddenly dips and actuates the brake g so that the rotation of the disk n is checked. The position of the stationary scale relatively to the pointer 0 indicates the strain at breaking point. The portions of concrete separated by the fracture do not fall apart, being held by the plate a. This enablesthe same specimen g to be used for testing the compression strength of the concrete. F or this purpose the specimen g is disengaged from the members ci and c, turned around, and rengaged With the same in the manner shown in Fig. 5, with the strut portions of the said members abutting against the concrete. The fracture 1^ closes up completely and accurately when this is done, so that for the purpose of the compression test the specimen is equivalent. to an unbroken piece of concrete. In replacing the scale beam h for the compression test the same is balanced on a knife edge t nearer the free end of the member c than the knife-edge previously used, so that the leverage is altered in accordance with the larger strains commonly borne by concret-e under compression. The compression test is carried out in the same Way as the tensile strength test, the beam 7L dropping when the concrete is crushed, as indicated at s in Fig. 5.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. Apparatus for testing concrete and the like comprising means for holding a test piece, a lever adapted to engage and bend a test piece held by said holding means, a scale beam poised on said lever so that the Weight oit' the beam tends to actuate the lever, means for loading one arm of said scale beam, means for maintaining said scale beam in equilibrium vvhile said arm is loaded, and

`means indicating the load on said beam at any given moment.

2. Apparatus for testing concrete and the like comprising means for holding a test piece, a lever adapted to engage and bend a test piece held by said holding means, a scale beam poised on said lever so that the Weight of the beam tends to actuate the lever, a

liquid receptacle carried by one arm of said scale beam, a liquid supply vessel adapted to deliver' liquid to said receptacle, a float in said supply vessel, means for maintaining Said beam in equilibrium Linder varying loads of liquid in said receptacle, and an indicating device connected to said ioat so as to move in proportion With the delivery of liquid from said supply vessel to said receptacle. f

3. Apparatus for testing concrete and the like comprising means for holding a test piece, a lever adapted to engage and bend a test piece held by said holding means, a scale beam poised on said lever so that the Weight of the beam tends to actuate thelever, means for progressively loading one arm of .said scale beam, means for maintaining said scale beam in equilibrium during progressive loading of said arm, an indicator moving in accordance with the progressive loading of said arm, and means automatically locking said indicator when the test piece is fractured by the bending strain.

4. Apparatus for testing concrete and the like comprising means for holding a test piece, a lever adapted to engage and bend a test piece held by said holding means, a scale beam poised on said lever so that the Weight of the beam tends to actuate the lever, means for progressively loading one arm of said scale beam, means for maintaining said scale beam in equilibrium during progressive loading of said arm, an indicator moving in accordance With the pro gressive loading of said arm, and a locking device connected to the scale beam for locking said indicator When the lever and beam are dropped consequent upon fracture of the test-piece.

5. Apparatus for testing concrete and the like comprising two members having hooked ends adapted to severally engage the ends of a test piece and struts adapted to abut against cent-ral parts of said test piece, a scale beam poised on one of said members so that its Weight tends to bend the test iece means for loadino" one arm of said scale beam, means for maintaining said scale beam in equilibrium While said arm is loaded, and means indicating the load on said beam at any given moment.

6. Apparatus for testing concrete and the like comprising two members having hooked ends adapted to severally engage the ends of a test piece and struts adapted to abut against central parts of said test piece, a scale beam poised on one of said members so that its Weight tends to bend the test piece, a liquid receptacle carried by one arm of said scale beam, a liquid supply vessel adapted to deliver liquid to said receptacle, al float in said supply vessel, means for maintaining said beam in equilibrium under varying loads of liquid in said recept-acle, and

an indicating device connected to said oat so as to move in proportion With the delivery of liquid from said supply vessel to said receptacle.

7 Apparatus for testing concrete and the like comprising tvvo members having hooked ends adapted to severally engage the ends of a test piece and struts adapted to abut against central parts of said test piece, a scale beam poised on one of said members so that its Weight tends to bend the test piece,

4means for progressively loading one arm of said scale beam, a turn buckle connected to the other arm of said scale beam and to the hooked member not supporting said beam, so that the beam can be kept in equilibrium by operating said turn buckle, and means indicating the load on said beam at any given moment.

8. Apparatus for testing concrete and the like comprising a plate having projections fixed to one surface thereof and end portions bent over toward said projections, so that said bent ends and projections can interlock With a mass of specimen concrete set on said plate; t-Wo members having hooked ends adapted to severally engage the bent ends of said plate, and struts adapted to abut alternatively against central parts of said plate or of a concrete mass set on said plate, according to the position of the plate and concrete; a scale beam poised on one of said members'so that its Weight tends to bend- RICHARD FRBER.

Witnesses JEAN GRUND, CARL GRUND.

Gopes of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

